I got the following results by using k-means algorithm. There are $10$ elements in Cluster $0$ and $3$ elements in Cluster $1$.
Do you think it makes sense and it might be an acceptable result? How could I explain it?
I can't see all your points on the plot.
It's possible to have a cluster with most points and one cluster with very few points since it is possible that most points are close to each other and we have another small clusters with only a few points.
However, you might like to explore the possibility of increasing the number of clusters.